BIOL 204 Lecture 17: Animal Development
Document Summary
Acrosomal reaction: discharge of hydrolytic enzymes from the acrosome, a vesicle in the tip of a sperm, when sperm and egg make contact; fast block to polyspermy. Egg activation: injections of ca2+ activates egg: mammals. Zona pulucida: extracellular matrix surrounding a mammalian egg. First cell division occurs 12-36 hours after sperm binding. Cleavage: converts zygote to a ball of cells by rapid cell division without significant growth: partitions cytoplasm of large fertilized egg into many smaller cells called blastomers. 2: first 5-7 produce blastula: hollow ball of cells surrounding blastocoel: fluid-filled cavity. Yolk is usually concentrated toward the vegetal pole and away from the animal pole. An eight celled embryo is formed: birds. Gastrulation: set of cells at or near surface of blastula moves to an interior location; cell layers established and primitive digestive tube is formed: sea urchin. Invagination: infolding of sheet of cells into embryo.
